1. Field of the Invention
The present invention relates to a method for bonding a non-oxide ceramic to a metal. More particularly, the present invention relates to a method for bonding a non-oxide ceramic to a metal, which is suitably used for bonding of a structural part of a machine, an electronic part and the like.
2. Description of the Prior Art
A method for bonding SiC, one of non-oxide ceramics, to a metal is disclosed in Nikkei Mechanical (published on July 4, 1983). According to this bonding method, a metal foil is inserted between SiC and a metal, the assembly is heated under pressure until the metal foil is fused, and the metal foil is diffused and infiltrated in the bonding interface between SiC and the metal to bond SiC to the metal. However, if heating is effected for bonding until the metal foil is fused, for the reasons described below, the strength of the bonded portion is reduced or cracks are readily formed in SiC.
(1) Since the metal foil is fused, the reaction of the metal foil with SiC becomes violent, and a silicide having a larger thermal expansion coefficient than that of SiC is formed in the interface between the metal and SiC. Accordingly, at the cooling step after the bonding operation, a large heat stress is generated because of the difference in thermal expansion among SiC, the silicide layer and the bonded metal.
(2) Since the solidification temperature of the fused metal foil is high and the difference between this solidification temperature and room temperature is very large, the heat stress is prominently increased.